David Cameron has revealed losing weight is his key personal goal for this year.

The Prime Minister, who is a keen tennis player, admitted he was keen to shed the pounds.

Asked for his top resolution for 2012, he told Now magazine: "Probably to lose a bit of weight, I think. That's the key one for me."

Giving a glimpse into his home life, Mr Cameron revealed that one night a week he has a date night with wife Samantha where the couple "either stay in and do nothing or go out on our own".

Describing his wedding and honeymoon as the best 24 hours of his life he told Now: "I can still remember pretty much minute by minute."

Admitting that he "can't bear" children's programme SpongeBob SquarePants, the premier said he has got his children into BBC wildlife series Frozen Planet instead. "Watching that's good for the karma," he added.

Mr Cameron gave the interview during his pre-Christmas visit to troops in Afghanistan and praised the "fantastic job" carried out by servicewomen.

He insisted he would be "delighted" but concerned if his daughters Nancy and Florence signed up for the armed forces.

"I'd be delighted. Like any parent, I'd be nervous and worried about what they were doing, but I've spent a day here in Kandahar and met women who are specialists at imaging, fantastic at logistics, engineers - it's not as if the army, navy and airforce are simply about fighting. You get an enormous amount of skills and training and a brilliant career."

Asked how he would cope if wife Samantha had that kind of role, he replied: "Well, she didn't travel as much as being in the armed services, but when she was design director at Smythson and I was an MP, sometimes she'd go off to New York for five days and I was left looking after the little ones, so it has happened. The children wouldn't starve or anything; the food was OK - I'm a reasonable cook - and they'd get to school on time, but I'm afraid the house would quite rapidly deteriorate. I'm not as good about tidying up as you go along as my wife is."